In product packaging using corrugated containers, formation of containers having flaps which are correctly aligned and non-skewed is required to meet manufacturer specifications and to provide packaging which is secure, protective, and of pleasing appearance. Certain applications require containers which are consistently and uniformly square and non-skewed. One such application is the use of corrugated containers to package bottled photographic processing chemicals, where the both the container and its bottled chemicals are inserted into a dedicated opening within a photographic processing machine. In this application, the container must be square and non-skewed within extremely tight tolerances. If the container is malformed, that is, out of square and or skewed out side of the required tolerances, it will not fit into the dedicated opening. Containers which are formed nearly within the required tolerances may possibly be inserted within the dedicated opening, but the chemicals may not be correctly aligned within the machine, causing machine malfunction.
Conventional rectangular corrugated containers are typically manufactured from a single piece of corrugated board, corrugated board, or similar material. They are die cut into a blank having a predetermined pattern and provided with indented fold lines to facilitate folding into a rectangular container. The container manufacturer usually folds the corrugated board blank along two of the fold lines so as to overlap and seal the leading and trailing lateral edges, forming a manufacturing joint. This process results in a flattened, or knock-down, product. A random sample of knocked-down containers are inspected by manual measurement using a ruler to insure that the product is formed to packager specifications and within required tolerances. Once the measurements are complete, the measured results are compared to the specifications. Containers measuring within the specifications are retained, and all remaining containers are discarded. Typically, product is shipped to the packaging facility in this compact, knocked-down form.
In instances where consistent and uniformly square and non-skewed containers are required, samples of the knocked-down corrugated board product are again inspected upon arrival at the packaging facility, and additional samples are inspected prior to use on forming-and-filling assembly lines. Upon passing inspections, the knocked-down corrugated board product is erected into a hollow tubular shape, filled, and then the bottom and top flaps are folded and sealed.
In this manufacturing process, there are two stages at which the quality of square and skew of the container are determined. The first stage is the folding of the corrugated board blank to form the manufacturing joint. If the blank is over folded, under folded, or folded so that the edges are not correctly aligned, the resulting container will not be square or will be skewed, or a combination of both. The second stage is when the bottom and top flaps of the tubular, filled container are folded and sealed. If these flaps are not correctly aligned with each other and with the side walls of the container, the container will not be square or will be skewed, or a combination of both. Typically, manufacturers of corrugated containers have difficulty providing containers which are properly aligned and non-skewed, and have no simple way to see that each and every container meets specifications.
Improvements in container design which allow containers to be more easily formed having square and aligned components would greatly improve packaging efficiency and quality. Specifically, a container design which addresses the issue of improvements in consistency in formation of both the manufacturing joint and the top and bottom flap fold are key to creating a consistently and uniformly square and non-skewed corrugated container.